Masterworks made in New York, courtesy of Bargemusic

There is an exceedingly fine point, as hard to perceive as Conrad’s “hair in the dark” from Lord Jim, where any new composition becomes part of the standard repertoire. Getting there has less to do with a certain number of performances and recordings than with a level of musical understanding, where the music, especially if experimental or avant-garde, is no longer a puzzle to solve but a set of ideas that players can clearly express and even enhance.

Thursday night at Bargemusic, cellist Michael Nicolas and pianist Aleck Karis, in a succinct but deep and fulfilling set, went a long way towards broadening the standard repertoire. They played modern American music, including a true rarity, with the command, musicality and implicit expressive comprehension that one commonly expects hearing Beethoven or Brahms. The relaxed precision and robustness of their playing let the music speak.

The concert had a title, “New York Composers,” part of Bargemusic’s Here and Now series, and before the playing began Nicolas spoke from the stage, expressing a feeling common amongst lovers of American classical music that contemporary works, as fine as they often are, have edged out the great period of experimental high modernism that extended from the end of WWII through the advent of minimalism.

In that mainstream were great symphonic composers like William Schuman, David Diamond and Peter Mennin, while at the cutting edge was the de facto New York School. Nicolas and Karis played pieces from two of members of that group, Earle Brown and Morton Feldman.

The evening offered a concentrated survey that, in just five works, managed to touch on the most important postwar directions in American music; atonality, neo-romanticism and experimentalism. Nicolas and Karis played Brown’s Music for Cello and Piano, Feldman’s Durations II, An Orbicle of Jasp by Charles Wuorinen, Ben Weber’s Five Pieces, and Elliott Carter’s Sonata for Cello and Piano.

Wuorinen, bucking the odds of history, has remained a dedicated atonalist, and his duet was written at the end of the last century. Regardless of how one takes atonal music, Wuorinen is a fine craftsman, and Orbicle has shape, form, direction, and is full of active, sympathetic dialogue. Nicolas’ phrasing was terrifically musical, giving a thoughtful purpose to each line.

Brown’s piece, from 1955, comes from the period when he was producing carefully made, thoughtful, and expressive graphic scores. His notation for this piece specifies pitches and coordinates them along the timeline of the music. Without meter and tempo, it came through in three sections of Fast-Slow-Fast, and Nicolas and Karis played the music with a pointillist feeling of exactitude and outstanding intellectual agility.

Weber was a colleague of Carter, Cage, and others, though his music is little known and rarely heard. He wrote a lot of atonal works, but the Five Pieces, from his early maturity, is less Webern and more Berg, full of romantic expression and, despite hints of atonality, always culminating section by section in a dramatic cadence. Cellist and pianist handled the virtuosic writing, which has an improvisational feel, with confidence and understanding.

Through three pieces spanning such wide aesthetic territory, the musicians seemed to be getting better, and moving deeper into each work. Durations II, from 1960, was exemplary. While Feldman had experimented with graphic scores, by this time he was returning to standard notation, though using minimal materials set out in sparse structures. Durations II has that aesthetic, along with the quiet one expects from Feldman. This was an exquisite, totally committed performance—the pulse was both ineffable and clear, as if the score itself was inhaling and exhaling to a consistent, relaxed rhythm. Every sound, even the softest, was as full and beautiful as possible.

Carter’s 1949 Sonata is one of his finest pieces, written at a time when the composer was finding his way to his own exceptional style, and one of the finest works of 20th century chamber music. The sound is romantic, but all Carter’s virtues are there in fledgling form, especially his polyphony, his interest in simultaneous musics, and the restless way things are constantly in flux, with hardly any of the material repeated in a noticeable way.

The four movements are traditional, with a fast opener, a pastoral, a lovely, impassioned ballad, and a furious finale. Something about the piece often pushes musicians toward a brittle quality, but Nicolas and Karis made it sound rich and proud.

Here and Now at Bargemusic continues 8 p.m. March 13, with bass trombonist David Taylor bargemusic.org